The present invention relates to a smoking article wrapper composition, and a method of making the smoking article wrapper composition, for significantly reducing ignition proclivity of the smoking article without adversely affecting smoking characteristics. The invention particularly relates to an improved wrapper paper for cigarettes wherein treated bands on the cigarette wrapper tend to cause the cigarette to self-extinguish if left or dropped on a substrate before igniting the substrate.
There is an ongoing concern in the industry to produce cigarettes having wrappers which reduce the ignition proclivity of the smoking article, or the tendency of the smoking article to ignite surfaces which come into contact with the lit smoking article. Reports have been made of fires attributed to burning cigarettes coming into contact with combustible materials. A justifiable interest exists in the industry to reduce the tendency of cigarettes, or other smoking articles, to ignite surfaces and materials used in furniture, bedding, and the like upon contact.
Thus, a desirable feature of smoking articles, particularly cigarettes, is that they self-extinguish upon being dropped or left in a free burning state on combustible materials.
It has long been recognized in the industry that the cigarette wrapper has a significant influence on the smolder characteristics of the cigarette. In this regard, various attempts have been made in the art to alter or modify the cigarette wrappers in order to achieve the desired tendency of the cigarette to self extinguish, or in other words to reduce the ignition proclivity characteristics of cigarettes. Prior references describe the application of fibrous slurries and/or film-forming solutions to cigarette paper to reduce permeability and control burn rate. It has been shown that when these materials have been applied in discrete bands around the circumference of the cigarette, the cigarette shows a reduced propensity to ignite a substrate and has an increased puff count.
For example, it is known from U.S. Pat. No. 4,452,259 to define at least one circumferential band on the wrapper of a smoking article which will hopefully cause the smoking article to extinguish under free burn conditions. The band is formed by applying a liquid substance or compound to the cigarette paper which has a liquid form in a temperature range of about 100.degree. C. to 200.degree. C. This reference teaches that, as the burning cone of the cigarette comes into contact with the band, the compound forms a liquid film on the cigarette paper which substantially restricts the flow of air to the burning coal.
U.S. Pat. No. 4,945,932 teaches another method of providing areas of decreased air permeability which cause the cigarette to self extinguish as the cigarette smolders or burns into the area of reduced permeability. The '932 patent teaches to form patterned or annular zones in the cigarette paper by multiple batonneing of the paper, for example, by use of an embossing calendar.
U.S. Pat. No. 4,077,414 discloses the use of printed bands of material on cigarette paper to control the burn rate of the cigarette. Although this reference does not particularly address ignition proclivity, it teaches to provide relatively narrow low porosity bands along the cigarette. The bands are formed by applying a gel-forming substance to the paper by painting, printing, or other coating techniques. The reference teaches that preferred gel-forming substances are those which form gels in water, such as gelatin, alginates, methyl cellulose, methylethyl cellulose and gums. Water insoluble substances such as lacquers and varnishes may also be used in an organic solvent.
U.S. Pat. No. 4,889,145 is another reference that teaches of providing areas of reduced porosity along the cigarette by applying a discontinuous coating of a porosity reducing composition. This reference is not particularly concerned with ignition proclivity of the smoking article, but with controlling the puff count and tar delivery of the smoking article. This reference also teaches to include a burn promoter in the wrapper to balance the effect of the discontinuous coating areas.
Various other applications and processes for reducing ignition proclivity of a cigarette are known as, for example, by U.S. Pat. No. 4,453,553; U.S. Pat. No. 4,480,650; U.S. Pat. No. 4,739,775; U.S. Pat. No. 4,489,738; U.S. Pat. No. 4,715,345; U.S. Pat. No. 2,666,437; U.S. Pat. No. 4,622,983; and European Patent Application 0 559 300 82.
Although, as described in the above cited references, various methods and processes are known for applying discrete bands of porosity reducing material to cigarette papers, such conventional techniques have a significant drawback in that a noticeable change in the smoking characteristics of the cigarette can be detected as the cigarette coal burns into the treated bands. This is particularly noticeable if a puff is being drawn as the burning coal reaches the division between a treated and non-treated portion of the paper. A noticeable difference in taste and smoke delivery is discernable by the smoker depending on the difference in permeabilities between the untreated and treated sections of the paper. Thus, what is needed, is a paper which remains effective in reducing ignition propensity or proclivity while minimizing the chance of discernable changes in smoke delivery and taste to a smoker.